Synchronization is a key technique in a mobile communication system. Searching with a synchronization code, the maximum correlation peak can be found through a correlation method; then the synchronization of subscriber signal is implemented or the most appropriate base station for the subscriber access is found. At present in a mobile communication system, the selected synchronization codes are pseudo-random codes. As the autocorrelation and cross-correlation value of these pseudo-random codes at the neighborhood where time-delay equals to zero are not equal to zero, so there is mutual interference between these pseudo-random codes.
Code division multiple access (CDMA) is an interference limited technology. When system synchronization is made with synchronization codes, the synchronization accuracy and veracity will be affected by interference, which includes interference caused by the multipath propagation of the synchronization signal itself and interference caused by the synchronization signals of other subscribers, etc.
For suppressing these interferences, a multi-user detection technique or other adaptive process methods are used at present, but they have high computation complexity and are difficult to realize. Therefore, with the present synchronization codes and without increasing the system complexity, it is difficult to implement a low interference, high accuracy and veracity of synchronization.